Pledging to ditch the policy during the campaign, he said: “We will do it very quickly. It is a catastrophe.”

Now he says he might simply reform it, keeping the ban on insurers denying coverage for pre-existing conditions and allowing young adults to be insured on parents’ policies.

Trump said he was persuaded to keep the elements by Mr Obama, who he previously accused of founding the Islamic State.

Jailing Hillary Clinton

Trump told supporters he would appoint a prosecutor to pursue criminal charges against his Democratic rival over her use of a private email server as Secretary of State, a scandal he said was “bigger than Watergate”.

At his rallies they chanted: “Lock her up, lock her up”. He said to her face that if he were in power: “You’d be in jail.”

But asked about the plan after his win, he said: “It’s not something I’ve given a lot of thought.”

After a single phone call with Clinton, Trump was apparently convinced she is actually not a politician whose “corruption is on a scale we’ve never seen before”, but instead that she “couldn’t have been nicer”.

The Mexico wall

Possibly the greatest symbol of Trump’s uncompromising approach. After claiming that Mexicans coming across the border are “bringing drugs. They're bringing crime. They're rapists”, he later declared: “We’re going to do a wall.”

Furthermore, he said Mexico would pay to build it, leading to supporters chanting: “Build the wall!”

Former House speaker Newt Gingrich, a Trump adviser, has now cast doubt on whether the new president would pursue its neighbour after all.

He said: “He’ll spend a lot of time controlling the border. He may not spend very much time trying to get Mexico to pay for it, but it was a great campaign device.”

Banning Muslims

There were cheers from Trump supporters, and global outrage, when Trump called for a “total and complete shutdown of Muslims entering the United States” in 2015.

This year the idea was recast as a ban on people from nations that were “compromised by terrorism”. After meeting Republican leaders this week a reporter asked Trump, “will you ask Congress to ban all Muslims from entering the country?”

He appeared to hear the question before thanking everybody and leaving.

Taxing China

While blaming foreign powers for the demise of US industry, Trump pointed a finger at Beijing. He suggested a tax on Chinese goods which “should be 45 per cent”. Senior policy adviser Wilbur Ross has now retreated.

“He’s been misquoted about the 45 per cent on China. Everybody says, ‘Oh, he’s going to slap 45 per cent tariff on everything out of China.’ That’s not what he said, and it’s not what he intends,” Ross told Yahoo Finance.

“What he actually said was if it turns out that the Chinese yuan is 45 per cent overvalued, or as much as 45, and if they won’t negotiate with us, then it may become necessary as a negotiating measure to threaten them with as much as a 45 per cent tariff.”

Not such a catchy chant for a campaign rally.

Iran nuclear deal

Iran is another foreign country that provided Mr Trump with a handy target during his election campaign.

In October Vice President-elect Mike Pence said a Trump administration would “rip up the Iran deal”.

But Trump adviser Walid Phares told the BBC after the election win: “‘Ripping up’ is maybe a too strong word. He’s going to take that agreement, it’s been done before in international context, and then review it.”

Other countries will pay for their own defence

Nato allies were left shaken after Trump appeared to say he could withdraw US backing for the alliance, if the he did not feel they were paying enough for defence.

He also said he would be willing to withdraw US military stationed in South Korea unless Seoul paid more.

After a phone call with Park Geun-hye, the South Korean President’s office reported that Trump pledged his commitment to defending South Korea under an existing security alliance.

Bringing back waterboarding

Trump left critics gobsmacked after saying during the campaign he would reinstate the use of waterboarding. The practice was made illegal after its use during the Bush era.

CNN reported that former Republican House Intelligence Committee chair Mike Rogers said this week that Trump’s remarks were just “campaign talk”.

Law and Order

He told supporters that any politician who failed to grasp the need for law and order is “not fit to lead our country”.

But despite repeating the phrase “law and order” four whole times at one rally, the rest of his divisive rhetoric has still had adverse consequences.

Rowdy protests have already led to dozens of arrests. Demonstrators across the US are preparing for a weekend of action. More than 10,000 people signed up to attend a noon march today in New York. Other activists have begun work to disrupt his inauguration, according to reports.